NEW ORLEANS -- Federal agents cited 15 charter boat companies that take anglers out into the Gulf of Mexico for a variety of violations, such as working without permits, fishing out of season and catching undersized fish.

The National Oceanic and Atmospheric Administration on Friday said it sent undercover agents on chartered trips across the Gulf and documented multiple violations.

Agency officials said charter boat companies in Florida, Texas, Louisiana and Mississippi were found operating in violation of state, Coast Guard and fishery laws.

Hal Robbins, a special agent in charge of the NOAA division in St. Petersburg, Fla., said the crackdown protects "law-abiding charter operations from unfair competition."

Bob Zales, the president of the National Association of Charter Boat Operators, said the undercover operation was the largest-ever against charter boats.

"There's a lot of people who try to skirt the law," Zales said. "Hopefully, this will send a signal."

Charter boats are big business, nowhere more so than in the Gulf of Mexico where fun seekers and weekend anglers rely on seasoned guides to show them where they can catch prized fish like king mackerel, red snapper, tarpon and tuna. A typical charter boat takes six passengers out for about $1,500.

The 15 boats were fined between $8,000 and $18,900 each, and all of them were cited for operating without a permit, said Charles Tyer, a NOAA special agent in Galveston who led the operation.

A moratorium on charter boat permits in the Gulf was put into effect in 2003. So, to get into business a new operator must buy or lease a permit from someone already with one. Permits do become available and can cost between $4,000 and $8,000, Zales said.

Zales said there are about 1,500 charter boats with permission to fish in federal waters and about 1,000 more licensed to operate in state waters, which are closer to shore.

"The federal government keeps track of the number of fish caught through permits, and if there are lots of boats fishing without permits it doesn't allow the tracking of fish," he said.

Ron Melvin, the 61-year-old owner of the "Backlash," a charter boat in Port Aransas, Texas, was cited for $18,900 in fines, the most of the 15 operators. Besides running without a permit, Melvin and the boat's captain, Melvin Stamper, were cited for using improper gear, fishing for red snapper during a closed season and taking undersized fish, Tyer said.

Melvin said the fines would drive him out of business. "$19,000! I don't think so," Melvin said. "They put me out of the business."

He said he was negotiating with NOAA lawyers to get the fines reduced. He said he believed he had purchased the required permits.

"In 2000, I Googled all the permits I thought I needed," Melvin said. "I'm totally in the dark about the whole thing."

Michael Hillman, the 51-year-old owner of the "White Hawk" boat in Galveston, was fined $15,000 for operating without a permit. Hillman complained that the federal government's rules were too restrictive.